Bruce first rode Speedway when he was 16 at Irwindale Raceway on the American west-coast. From novice status, he quickly established himself in the US National Championships, twice finishing in the top three positions. In 1976 he toured Israel and in 1977 Australia and New Zealand, before being lured to Cradley Heath Heathens in 1978 by Dan McCormick and Derek Pugh.

Also in 1979, Penhall rode in the World Pairs Championship Final at the Vojens Speedway Center in Denmark. Originally to be partnered by Kelly Moran (the pair had finished second in their semi-final round to qualify) until Moran had to withdraw due to injuries from a practice crash, Steve Gresham was called in as Moran's replacement. However, Gresham was left stranded at the Heathrow Airport in London (as was a hurried third replacement Ron Preston), Penhall was forced to ride the meeting with the reserve riders as teammates. He would score 14 out of a possible 18 points with four wins and two third places to finish in 5th place.

Also in 1981 Penhall partnered fellow American Bobby Schwartz to win the World Pairs Championship in Katowice, Poland, and alongside fellow 1981 World Finalist Erik Gundersen of Denmark (himself a Future multiple World Champion), led Cradley all the way to their first ever league title victory, topping the individual league averages on the way. On top of a clean sweep of all the SWAPA personality awards was a special citation from US President Ronald Reagan.

Bruce Penhall's debut in CHiPs came in the season 6 episode "Speedway Fever", which mainly concentrated on his character Nelson winning the 1982 World Final at the LA Coliseum. Scenes were shot in the pits in between races and actual footage of the final was shown in the episode.

In 1985, Penhall travelled to Sydney in Australia to read the lesson at the funeral of rider Billy Sanders after the Australian champion committed suicide at his home in Ipswich (England). The two riders were close friends and Bruce is the godfather of Sanders' children Dean and Belinda. In a sad twist, Dean Sanders who was 10 years old and in school just 10 miles from the Sanders' Ipswich home when his father took his own life, would later also commit suicide.

Penhall was well known for his role as Cadet/Officer Bruce Nelson in the final season of the NBC television series CHiPs and in the role of Bruce Christian in the 1989 film Savage Beach and five of the movie's sequels, including Hard Hunted (1993). Penhall reprised his role as Bruce Nelson in the 1998 TNT television movie CHiPs '99 and has made guest appearances on shows such as Just Men!, The Facts of Life and Renegade.

Penhall's son Connor (born 1990) was killed by a drunk driver in 2012 while working on a freeway. Bruce later got himself a tattoo in memory of his late son.

In 1999, Penhall was inducted into the A.M.A. Motorcycle Hall of Fame. In 2008, Bruce took over as joint promoter, along with Jeffrey Immediato, of speedway racing events at 'The Grand at Industry Hills' race track in City of Industry, California.

Penhall went on to achieve his one last speedway ambition which was to win the Individual World Final on his home soil in America. He did this by winning his last 4 rides (after finishing 2nd in his first) and finishing with 14 points for the night. He then did what many expected and effectively retired from international speedway on the podium as reigning World Champion.